Studies have continued to find out the meaning of each brainwave form by measuring electrical activity of the brain and thus obtaining a brainwave and detecting characteristics, such as frequency and amplitude, of the brainwave. Recently, brain fingerprint technology as one of the studies using brainwaves has been gaining a lot of attention but is still in its early stage.
In this regard, Korean Patent Laid-open Publication No. 10-2004-0019013 (entitled “Method and apparatus for brain fingerprinting, measurement, assessment and analysis of brain function”) discloses a method of detecting information stored in the electronic signals originating in the brain. According to the above patent, the method of detecting information stored in the brain of a subject comprises: presenting to the subject with stimuli including: probe stimuli relevant to a situation under investigation for effecting in the subject a specific brain response when the subject has knowledge thereof, irrelevant stimuli not relevant to the situation, and target stimuli having at least one of the following characteristics: they are identified to the subject as being noteworthy; and they are relevant to the situation under investigation; assigning a task that involves discriminating between target stimuli and standard stimuli and communicating this discrimination through an overt response; detecting an electrical brain response from the subject in response to each of the stimuli; analyzing the electrical brain responses for uncovering the specific brain response therein; and comparing the electrical brain responses due to the probe, irrelevant, and target stimuli for detecting the presence or absence of the information in the subject's brain based on the presence or absence of the specific brain response in response to the probe stimuli.
As such, the conventional brain fingerprint technology has a limitation in that electroencephalographic (EEG) signals are simply used as conditions for inference of a subject's condition, whether the subject told a lie or not, or certain information stored in the brain.
Meanwhile, various technologies of processing brain-machine interfaces by analyzing parameters caused by cognitive properties of EEG signals have been developed. As a cognitive property of EEG signals, an event-related potential (ERP) which is a brain potential generated in relation to a presented stimulus or event may be used. A demand for brain fingerprint technology capable of using the ERP as unique identification information for identifying a subject, such as fingerprint (i.e., brain fingerprint) and a method of applying the brain fingerprint technology to an actual brain-machine interface has been increased.